Fotorezystor - a Huge breakthrough in the world of electronics was the discovery of the electrical properties of semiconductor materials. This material, often crystalline, which is the conductivity (electric conductivity) can be changed in wide range by introducing impurities, temperature change or change in the intensity of light falling on the semiconductor. Electronic elements, which use the photovoltaic properties of semiconductors are fotorezystory also known as fotooporniki.
One of the most basic laws of physics, which is known to every Amateur or professional dealing with electricity is ohms law which shows the dependence of the magnitude of the current flowing in a circuit from voltage and resistance. Element, electronic, which will allow us the right to pass on the practice is a resistor, and its main parameter is the resistance – resistance. In those days, when leaders in electronics, semiconductors are due to their properties constituted a modified version of the resistor – fotorezystor. Fotorezystory that the semiconductor elements are built up of layers of semiconductor deposited on the surface of the insulation. The photosensitive material separates two electrodes are connected with the conclusions. The image surface is covered by a transparent window. Under the influence of the change of intensity of illumination fotooporniki change their resistance depending on the direction of the applied voltage. The increase in light intensity leads to a decrease in resistance, and thus increasing the intensity of the flowing current at a constant voltage. Fotooporniki are characterized by a linear family of characteristics prądowo – voltage, which is very welcome in electric circuits.
For the main parameters describing fotorezystory include:
- sensitivity spectrum, i.e., the electrical resistance depends on light
- dark resistance "RD", that is, the resistance fotorezystora in the environment without lighting
- resistance "Rxx" where "xx" indicates that the illumination level in Lux (lx). This resistance fotoopornika for a certain value of lightness. Manufacturers index cards, you can look, for example, the resistance R10, R50. Called also the resistance widną.
- the coefficient "n" is defined as the ratio of the resistance dark resistance for a given value of illumination, for example, n=RD/R50
- maximum operating voltage
- maximum power
- switching time
- working temperature.
Because of the very high sensitivity and the simplicity of the measuring system, fotorezystory is used very often to measure the temperature by measuring the radiation intensity. Perfect thus, in the systems of heat detection, fire-fighting systems. They can also be used for systems, which depends on the time of day, for example, automatic opening and closing of shutters in Your home, lighting control. In Botland in addition to the classic fotorezystorów 100 MW and rezystancjach bright in the following ranges: 5-10 k?, 10-20 k?, 20-30 k?, 50-100 k?, you will also find fotooporniki in the form of modules were developed to interact with the Arduino. The module has an analog output that can be connected directly to the set execute and create your projects, opening up new applications fotorezystorów.